1. Field of the Invention
The present invention relates to a PTC (Positive Temperature Coefficient) element having a semiconductor ceramic composition having a positive resistance temperature coefficient, which is used for a PTC thermistor, a PTC heater, a PTC switch, a temperature detector and the like, and a heating-element module using the same.
2. Description of the Related Art
Hitherto, as a semiconductor ceramic composition having a positive resistance temperature coefficient, one described in Patent Document 1 has been known. Since such a semiconductor ceramic composition has a characteristic that a resistance sharply increases at a high temperature more than the Curie point, the composition is used for a PTC thermistor, a PTC heater, a PTC switch, a temperature detector and the like.
Since semiconductor ceramic compositions having a PTCR (Positive Temperature Coefficient of Resistivity) characteristic, which have been currently put to practical use, contain Pb, there is a concern of environmental pollution and hence a Pb-free semiconductor ceramic composition and a PTC element using the same have been desired. Moreover, a light weight and thin type is a trend of the times and thus a PTC element, which is thin and has high withstand voltage, has been desired at uses in high-voltage control systems such as electric vehicles.
Patent Document 1: JP-B-48-27556